GB1572775A - Stabilization of deodourized edible oils - Google Patents

Description

PATENT SPECIFICATION ( 11) 1 572 775

n ( 21) Application No 6355/78 ( 22) Filed 17 Feb1978 ( 19), Z ( 31) Convention Application No 769809 ( 32) Filed 17 Feb 1977 in ( 33) United States of America (US) ' % > ( 44) Complete Specification Published 6 Aug 1980 l i (n ( 51) INT CL 3 C 11 B 3/14 -I ( 52) Index at Acceptance C 5 C 5 B 6 o ( 54) STABILIZATION OF DEODOURIZED EDIBLE OILS ( 71) We, CHEMETRON CORPORATION, a Corporation organized and existing under the laws of the State of Delaware, United States of America, of 111 East Wacker Drive, Chicago, Illinois 60601, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be

performed, to be particularly described in and by the following statement: 5

Oils and fats, for a long time, have been deodourized by treatment with steam, with the exclusion of oxygen, in batch, semi-continuous and continuous processes using apparatus appropriate to each; see, for example, U S 3,693,322 and Kirk-Othmer, "Encyclopedia of Chemical Technology", Fats and Fatty Oils, Vol 8, pages 776-811, Interscience Publishers, New York ( 1965) Virtually all the vegetable oil entering edible fat products is subjected to 10 deodourizing treatment for flavour improvement and odour removal.

Deodourization is a process of steam distillation in which the relatively non-volatile oil is maintained at a high temperature and under reduced pressure while it is stripped of the relatively volatile constituents responsible for off-flavor and odour In the manufacture of edible products, deodourization is almost invariably the last step in processing before 15 finishing and packaging.

Preferably, prior to deodourization, the edible oil is usually subjected to refining, usually alkali refining, bleaching or decolorization, optionally followed by hydrogenation These techniques are described in Kirk-Othmer Loc cit.

Most edible oils, in their crude state, have natural anti-oxidants It has been noted in the art 20 that processed edible oils, especially after being steam deodourized, tend to have an increased tendency toward oxidation, rancidification or, what is commonly referred to in the art as, reversion.

Reversion of edible oils is known to be accelerated by contact with prooxidant metals or their salts, such as for example, copper, iron, lead, manganese and cobalt 25 It is noted that 316 stainless steel, which contains molybdenum is and has been for some time preferred for the construction of deodorizing vessels, because oils deodourized in vessels made from 316 stainless steel exhibit less reversion than those processed in 304 stainless steel or carbon steel.

It has now been discovered that conducting steam deodourization of edible oils in contact 30 with a stabilizer which is molybdenum metal, molybdenum oxides or mixtures of said metal and said oxides reduces the initial peroxide value of the oil and retards the subsequent increase in peroxide value of the oil in storage, as compared to the same oil steam deodourized in the absence of molybdenum metal or molybdenum oxide This effect is noted even in the presence of pro-oxidant metals 35 The amount of molybdenum metal or molybdenum oxide contacted with the edible oil is a peroxide value stabilizing amount which is herein defined as an amount sufficient to provide a reduction in the initial peroxide value, as compared to the peroxide value of the same oil treated in the absence of the stabilizer The exact amount of stabilizer necessary apparently varies with the amount of unsaturation present in the oil, and is apparently particularly 40 dependent on the presence of linolenic acids It is noted that the relative rate of oxidation in the series of linoleic acid, linolenic acid and arahidonic acid increases with the addition of each active methylene group Soybean oil is particularly subject to reversion and requires the presence of significantly more stabilizer than does palm oil which has lower unsaturation, and particularly lower levels or the absence of significant amounts of linolenic acids 45 2 1,572,775 2 Typically, the stabilizing amount of molybdenum metal or molybdenum oxide employed with an oil such as soybean oil is an amount to provide a surface area of between about 33 square inches to about 66 square inches of metal or metal oxide per litre of oil For oils inherently more stable than soybean oil, lesser amounts of molybdenum can typically be employed In some cases, amounts as low as 4 square inches per litre or even less can have a 5 useful effect.

Preferably, the amount of molybdenum metal or molybdenum oxide employed is an amount sufficient to provide a peroxide value in the deodourized fat or oil, after three days accelerated aging in the Oven Test, (determined by AOCS Official Method Cd 8-53) of less than about 10 and most preferably less than about 5 10 The molybdenum metal or molybdenum oxide may be used per se or may be coated or impregnated on a support such as alumina or other inert support material such as those known in the catalyst industry.

The molybdenum or molybdenum oxide is preferably employed in a form that presents a substantial surface area for contact with the edible fat or oil being treated, for example, 15 strands of wires, chips, granules, etc Since it is obviously desirable to separate the molybdenum or molybdenum oxide from the oil after treatment is complete, it is preferred where very finely divided material is employed, which will not readily separate from the oil, that the finely divided material be fixed to an inert carrier or support material.

The molybdenum metal or molybdenum oxide is contacted with the fat or oil during the 20 steam deodourization process in any practical manner Usually, it is placed at the bottom of the steam distillation vessel, for example, in the tray described in U S A Patent Specification

3,693,322 Since in the steam deodourization process the steam provides substantial agitation of the fat and oil, adequate contact with the molybdenum metal or molybdenum oxide is readily accomplished 25 Alternatively, if desired, a portion of the wetted surface of the deodourizer surface can be constructed of molybdenum, thereby providing the molybdenum surface area necessary to provide the desired stabilizing effect.

The steam deodourization processes known in the art are conducted at an elevated temperature While the temperature is not unduly critical and is governed, in part, by the type 30 of oil being treated, it is preferred that the edible oil be contacted with the stabilizer at a temperature above about 400 'F, and preferably between 440 and about 540 'F.

While the process of the invention can be practised in conjunction with any of the known steam deodourization processes, the preferred process and apparatus is that described in U S A Patent Specification 3 693 322 which is hereby incorporated by reference 35

The edible oils which can be stabilized by the process of the invention include edible vegetable oils, such as the oleic-linoleic acid oils, which are of medium, but rather variable unsaturation (iodine values varying from about 50 for palm oil to about 120 for corn oil with no fatty acids more unsaturated than linoleic) and include palm oil, cottonseed oil, peanut oil, corn oil, safflower oil, sesame oil and sunflower oil; Erucic acid oils (containing minor 40 amounts of linolenic acid) including rapeseed oil, ravision oil and mustardseed oil; as well as linolenic acid oils, most importantly soybean oil (see Kirk-Othmer loc cit).

While vegetable oils including unhardened oils, hardened oils and winterized oils are of particular interest, the process of the invention is also applicable to other edible fats and oils of commerce such as animal fats and whale and fish oils 45 The invention is further described in conjunction with the following examples which are to be considered illustrative, rather than limiting the invention to their details All parts and percentages throughout the specification are by weight unless otherwise specified All temperatures are degrees Farenheit unless otherwise specified.

A number of deodourization processes, described in the following examples, were con 50 ducted in a 750 ml glass wall deodourizer with internal wetted metal parts constructed of metals set forth below The design and functioning deodourizer were as described in U S A Patent Specification 3,693,322, previously incorporated by reference Peroxide Values were determined by A O C S Official Method Cd 8-53.

EXAMPLE l 55

In this group of runs, the oil treated was refined and bleached undeodourized soybean oil where 1 oz molybdenum wire was employed, the wire was 1/8 " in diameter, 1/2 " long having 4 8 square inches of contact surface within the oil being deodourised.

Sample No 1 O Refined and bleached undeodorized soybean oil.

Test Run 1 1 All wetted metal parts made of 316 stainless steel including the heating coil 60 Test Run 1 2 All wetted metal parts made of 316 stainless steel including the heating coil plus 1 oz molybdenum wire resting on tray bottom.

Test Run 1 3 All wetted metal parts made of 316 stainless steel except the heating coil which was made of 304 stainless steel.

Test Run 1 4 All wetted metal parts made of 316 stainless steel except the heating coil 65 3 1,572,775 3 which was made of 304 stainless steel plus 1 oz molybdenum wire resting on tray bottom.

Test Run 1 5 All wetted metals made of 316 stainless steel except the heating coil which was made of high carbon steel tubing.

Test Run 1 6 All wetted metal parts made of 316 stainless steel except the heating coil 5 which was made of high carbon steel tubing plus 1 oz molybdenum wire resting on tray bottom.

Sample No 1 7 Refined and bleached undeodourized soybean oil (Same lot as 1 0) Test Run 1 8 Repeat of Test Run 1 6.

All wetted metal parts made of 316 stainless steel except the heating coil 10 which was made of high carbon steel tubing, plus 1 oz molybdenum wire resting on tray bottom.

Test Run 1 9 Repeat of Test Run 1 5 All wetted metal parts made of 316 stainless steel except the heating coil which was made of high carbon steel tubing.

All the deodourization runs were conducted by deodourizing a 750 ml refined and 15 bleached soybean oil for 1 hour at 485 F using 3 % stripping steam.

SAMPLE NUMBER PEROXIDE VALUE FREE FATTY ACID 2 Initial' 24 48 72 96 120 144 168 Hrs.

1-0 2 9 13 5 21 1 32 8 70 2 82 5 0 04 % 1-1 85 16 6 26 3 26 3 62 4 77 6 0 018 % 1-2 1 1 5 4 14 2 24 9 36 7 78 3 0 014 % 1-3 54 5 0 10 2 21 1 45 8 54 5 0 014 % 1-4 22 1 5 12 6 18 7 39 1 59 2 0 013 % 1-5 1 52 4 6 16 3 36 5 34 8 1-6 2 61 1 7 9 6 21 7 30 0 0 014 % 1-7 3 70 9 7 16 5 33 5 63 0 0 049 % 1-8 22 1 0 5 1 16 9 28 7 38 3 0 014 % 1-9 22 1 0 1 2 8 0 18 0 22 0 0 014 % 1 1-4 hours after deodourization 2 Free Fatty Acids were determined by Ca 5 a 40 from AOAC; determined on freshly deodourized sample -.1 t O -4 j 1,572,775 EXAMPLE 2

In this group of runs, the glass walled deodourizer was equipped with internal parts of 316 stainless steel, except that the heating coil was 304 stainless 5 The materials treated were refined and bleached soybean oil, cottonseed oil, and sunflower oil, as well as bleached palm oil.

The molybdenum employed was in the form of the wire described in Example 1.

The deodourizer was operated as in Example 1.

Test Run ( 1-10): 750 ml refined and bleached soybean oil without molybdenum present 10 Test Run ( 1-11): 750 ml refined and bleached soybean oil with 1 oz molybdenum present.

Test Run ( 1-12): 750 ml refined and bleached cottonseed oil with 1 oz molybdenum present.

Test Run ( 1-13): 750 ml refined and bleached cottonseed oil without molybdenum present.

Test Run ( 1-14): 750 ml bleached palm oil without molybdenum present 15 Test Run ( 1-15): 750 ml bleached palm oil with 1 oz molybdenum present.

Test Run ( 1-16): 750 ml refined and bleached sunflower oil with 1 oz molybdenum present.

Test Run ( 1-17): 750 ml refined and bleached sunflower oil without molybdenum present.

Test Runs ( 1-18, 1-19): 750 ml refined and bleached soybean oil with 3 ozs molybdenum 20 present.

Test Run ( 1-21): 750 ml refined and bleached cottonseed oil with 3 ozs molybdenum present.

Test Run ( 1-22): 750 ml refined and bleached sunflower oil with 3 ozs molybdenum present 25 ON PEROXIDE VALUE 72 96 120 144 168 192 216 26.3 24.9 39.8 44.8 39 29.1 7.8 5.4 19.5 29.4 18.9 18 13.2 43.5 52 51.5 44.8 14.7 10.2 23.9 14.3 11 48.3 56.9 66 56 16.8 15.2 16 62.4 36.7 73.5 80.7 63 65.2 15.8 41.4 43.1 14 77.6 78.3 225 17 l 31 116 103 358 472 19 240 (Hrs) 34.6 21.9 143 131 18 FREE FATTY ACID 018 % 0.14 % 024 % 0.15 % 0.15 % 01 % 024 % 017 % 013 % % SAMPLE NUMBER 1-1 1-2 1-10 1-11 1-12 1-13 1-14 1-15 1-16 1-17 1-18 1-19 1-21 1-22 INITIAL 1.1 1.4 1.6 1.03 1.02 26 2 0 0 0 0 0 0 0 7.2 5.4 22.2 24.7 7.61 5.6 6.3 10.9 9.3 4.9 5.7 4.3 16.3 14.2 30.6 36 25.5 19.5 5.2 3.7 18.8 19.7 19.4 18.3 6.5 9.3 Ln ON 1,572,775 EXAMPLE 3

In this group of runs, the glass walled deodourizer was equipped with internal parts of 316 stainless steel, except that the heating coil was 304 stainless The oil treated was refined and bleached soybean oil The object of these tests was to demonstrate the effect molybdenum surface area as it relates to stabilization of the oil The following samples were deodourized as in the previous examples using the indicated increasing amounts of molybdenum surface.

Test Run ( 2-A) 750 ml oil with 1 oz molybdenum wire 4 8 square inches surface area.

Test Run ( 2-B) 750 ml oil with 3 oz molybdenum wire 14 8 square inches surface area.

Test Run ( 2 C) 750 ml oil with 1 oz molybdenum chips 51 0 square inches surface area 10 Test Run ( 2-D) 750 ml oil with 0 5 oz molybdenum chips 25 5 square inches surface area.

Test Run ( 2-E) 750 ml oil with 1 5 oz molybdenum chips 75 6 square inches surface area.

After deodourization trace metal analysis for molybdenum on both the deodourized oils and the undeodourized oil show no molybdenum levels above 0 1 ppm.

The deodourized samples were subjected to a ten day accelerated aging test at 630 C This 15 test is known in the industry as the Oven Test or Schaal Test Experience has shown this test to be equivalent to 1-2 months storage at 90 "F or 2-4 months at 70 "F.

Figure 1 shows the results plotting peroxide value vs time.

Figure 2 shows peroxide value vs surface area of molybdenum contacted at 5 and 7 days 20 As can be seen from Figure 2 oil stability appears to display a threshold value above which an increase in molybdenum surface area contacted significantly affects oil stability.

While there has been described above the invention and what are now considered its best embodiments it is understood that other materials and equipment such as described above may be substituted for those exemplified All parts and percentages set forth are by weight 25 unless otherwise specified.

Claims (9)

WHAT WE CLAIM IS:-

1 A process of steam deodourizing edible animal and vegetable fats and oils which comprises conducting the steam deodourization in contact with a peroxide value stabilizing amount, as defined hereinbefore, of molybdenum metal, molybdenum oxides or mixtures of said metal and said oxides, which has been added to the apparatus in which the steam 30 deodourization is conducted.

2 A process, as in claim 1, where molybdenum metal is employed.

3 A process, as in claim 1, where the edible fat or oil is heated to a temperature of at least 4003 F.

4 A process, as in claim 3, where molybdenum metal is employed.

A process, as in claim 1, where the oil is an unsaturated vegetable oil.

6 A process, as in claim 5, where molybdenum metal is employed.

7 A process, as in claim 5, where the edible oil is heated to a temperature of at least 4 400 F

8 A process, as in claim 7, where the oil is selected from the group consisting of soybean 40 oil, cottonseed oil, palm oil, and sunflower seed oil, and sunflower seed oil and rapeseed oil.

9 A process, as in claim 1, where the amount of molybdenum or molybdenum oxide has a surface area between 33 square inches and 66 square inches per litre of oil being contacted.

MARKS & CLERK Chartered Patent Agents 57-60 Lincolns Inn Fields, London, WC 2 A 3 LS.

Agents for the Applicants Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey, 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A IA Yfrom which copies may be obtained.

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